1. Field of the Invention
The present invention relates in general to hatch covers for railcars. In particular, the present invention relates to improved hatch cover assemblies providing ease of opening.
2. Description of the Related Art
Railcars have long been employed to transport granular material such as grain. Such railcars typically have a series of openings, or a single opening, in the top of the railcar through which the grain may be loaded, with the openings commonly being referred to as troughs. Associated with these openings are one or more hatch covers which close and seal the openings during transport.
The hatch covers are typically provided in sets of three or more, even where a single elongated opening is employed. The hatch covers are hinged along one or both edges, with the hinges for the hatch covers being substantially coaxial. The edges of adjacent hatch covers are in close proximity. In a first prior art method, a series of battens are supplied to overly and provide a seal between these edges, and at the outermost ends. As such, a railcar having four covers would employ five battens.
While this arrangement has been found serviceable it does have associated problems. For example, it is necessary to release and pivot the battens away from the hatch covers in a separate operation prior to opening the hatch cover. Additionally, the pivot of the batten is subject to wear such that metal portions of the batten tend to contact the hatch cover. The battens are typically formed of steel, while the hatch covers are normally formed of aluminum or fiberglass. As such, the battens tend to damage the hatch cover in time, due to this wear.
According to a second prior art method, best illustrated by U.S. Pat No. 3,664,270 to Stark et al., the ends of the covers overlap to provide the seal. In the Stark patent there are five covers, with the centermost cover overlapping the adjacent covers at each of its ends. Similarly, at their opposite ends these adjacent covers overlap the outermost covers to which they are adjacent. Another example of overlapping covers is shown in U.S. Pat. No. 5,355,808 to the current inventors. In this Early patent, the overlapping pattern may take various forms, but it is preferred that each cover overlap its adjacent cover along a common end. In other words, the right hand end of the covers will always overlap the left hand end of an adjacent cover.
These overlapping covers overcome the disadvantages of the batten bars discussed above. However, due to the overlapping arrangement, it is necessary to open the covers in a particular order. For example, the Stark arrangement would require the operator to open the centermost cover first, then travel to the right to open the adjacent cover, then travel to the right again to open the rightmost cover. After this, the operator must travel to the left to open the other adjacent cover, then travel left again to open the leftmost cover. The Early arrangement reduces the amount of travel needed, as the operator may open the covers sequentially from one end to the next, without any backtracking.
While these arrangements, and in particular the Early arrangement, are improvements over the prior art, there are still further improvements possible. For example, while the overlapping provides good seals with improved longevity, there is still the need to open the covers in a particular order. This may necessitate opening several covers when only one cover was needed open.
Additionally, with all cover arrangements there is the desire to permit limited access to the interior of the railcar, for example to obtain a small sample of grain, with a minimal amount of effort. For most arrangements, it is necessary to open an entire cover. It is possible to provide a hatch within the cover, but this of course drives up the cost of the cover, and increases the risk of cargo contamination through seal failure around the hatch.
Another problem associated with all cover arrangements is the weight of the cover, which must be physically lifted. While contemporary covers are typically formed of aluminum, they are still an appreciable weight to lift. Furthermore, this lifting of the covers is performed on the top of the railcar, increasing the possibility of injury.